Malicious RTF — malware analysis report

Static analysis result for SHA-256 77ba20973b70a74d…

MALICIOUS

RTF

5.1 KB First seen: 2022-11-14
MD5: 29ffbffad52f6eb050f7eac5ed609b0b SHA-1: 5d4336f03ce3c00ae5b510e5c5f91eb5d76d291d SHA-256: 77ba20973b70a74dbf4252d0a814dca465f8e963fcb69f63e2ef29edd78c3c9b
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains an embedded OLE object that triggers the Equation Editor vulnerability (CVE-2017-11882). This exploit is designed to execute arbitrary code upon activation, likely leading to a second-stage payload download or execution. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this attack vector.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000070.bin
2fab7fa936f677e1e8096c8195423d0f63aa22b8629018436f42e2532d4b839b		 rtf-objdata-decoded RTF \objdata at offset 0x70 2352 bytes

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